<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title></title>
		<style type="text/css">
			div#box{
				text-align: center;
			}
			div#box div#btn{
				margin: auto;
				width:50px;
				height:50px;
				line-height:50px;
				background-color: #ddd;
				border-radius: 100%;
				color:#fff;
				cursor:pointer;
			}
		</style>
	</head>
	<body>
		<div id="box">
			<div id="btn">开</div>
			<img id="img" src="img/pic_bulboff.gif" >
		</div>
		<script type="text/javascript">
			(function(){
				var btn = document.querySelector('#btn')
				var img = document.querySelector("#img")
				btn.onclick = function(){
					console.log("this:", this)
					if(this.innerHTML == "开") {
						img.src = "img/pic_bulbon.gif";
						this.innerHTML = "关"
						this.style.backgroundColor = "green"
					} else {
						img.src = "img/pic_bulboff.gif"
						this.innerHTML = "开"
						this.style.backgroundColor = "#ddd"
					}
				}
			}());
		</script>
	</body>
</html>
